\startMPpage
input snail.mp;
Node a, b, c, abc, d;
a := other("a", fullsquare xysized (2cm, 1cm));
b := other("b", like a);
c := other("c", like a);
as_planet(b, a, "bottom"); as_planet(c, b, "bottom");
abc := a +++ b +++ c;
d := other("d", like abc);
as_star(d, abc, "right");

forsuffixes i = b, c: valign(i, a); endfor;

draw_each a, b, c, d;
\stopMPpage
